1. Field of the Invention
The present invention relates to an information medium carrying system, and more particularly to positioning system and method for positioning an information medium carrying device at one of a plurality of medium processing sections.
2. Description of the Related Art
In Japanese Patent Laid-Open Publication No. 5-325355 disclosed a carrying and storing mechanism for cartridge-type recording mediums. In a cabinet of a medium carrying apparatus, storage shelves having a plurality of storage cells for housing cartridge recording mediums, are arranged facing each other. An access mechanism for carrying a medium grasping device is provided between the opposing shelves. Near the storage shelves are provided a recording/reproducing device for recording and reproducing data on the recording mediums, and an insert-eject opening through which a recording medium is inserted to an ejected from inside.
A conventional medium carrying apparatus as described above is generally equipped with a positioning means which is used when the access mechanism carries the medium grasping device to one of medium processing sections, for example, the recording/reproducing device, the storage cell, the insert-eject opening or the like. The positioning means is comprised of positioning flags fixed to each of storage shelves, and flag detection sensors provided on the access mechanism side. The medium grasping device can be carried to a desired processing section while the flag detection sensors detecting the positioning flags.
Actually, the access mechanism which determines the position of the medium grasping device, the processing sections such as the storage cells, and the position detecting sensor are provided separately from each other. As a result, variations in precision when assembling the respective elements of the configuration cause positioning errors.
As a conventional example, a positioning method using an absolute positioning sensor and a relative positioning sensor has been proposed in Japanese Patent Laid-Open Publication No. 4-20403. According to this positioning method, the absolute positioning sensor is used for a first positioning mode and, if the first positioning fails to be successfully ended, then a relative error is measured and the relative positioning sensor is used for a second positioning mode to correct the relative position error.
However, this type of positioning method needs much more time for positioning in the case where amount of storage of the recording medium is increased by the addition of another cabinet having similar processing sections as described before.
Another method of solving this problem is to estimate in advance the amount of error due to variation in assembly precision for each processing section, and to store these errors as corrective values. Then, the operation of the access mechanism is corrected as appropriate based on the corrective values to position the medium grasping device at a desired processing section.
However, with this conventional positioning correction method, when amount of storage of the recording medium is increased by the addition of another cabinet having similar processing sections, the number of points at which the amount of error needs to be measured in advance becomes greater. As a consequence, the error at all processing sections must be measured when setting up the medium carrying apparatus, or when performing maintenance of the apparatus. This results in disadvantages that measurement takes considerable time and is complex.